One major difficulty with baby cribs is that as the child grows in height and physical abilities, it is necessary to set the mattress lower and lower with respect to the top of the crib gate. This is done for the child's safety, to keep him from crawling over the gate and out of the crib. Most cribs can be adjusted to account for this. This is typically done in a “set it and leave it” manner, meaning that the adjustment is a relatively involved procedure and the mattress is meant to be adjusted (lowered) once and then left in its new height setting.
Aside from the fact that the mattress adjustment is cumbersome and difficult to make, the main difficulty arises from the fact that, as the mattress is required to be set lower and lower, the child himself is getting taller (and heavier). Since the mattress is set at a low height permanently (for all intents and purposes), as the weight of the child increases, the parent carrying the child must bend down to lay the child on the mattress. The strain on the parent's lower back caused by lowering a heavy sleeping child over a crib gate and down onto a low-set mattress can be incredibly taxing, even on a healthy adult. If that adult happens to be among the millions with back problems or other debilitating diseases, the daily challenges can be almost insurmountable.
Previous attempts at addressing this problem were made with the introduction of the lowering gate. Such crib has a front gate designed as a two-piece assembly which allows the top half to be slid or swung down. This design has been banned in the United States due to incidents of unintended and sudden gate lowering, which resulted in injuries to children. Therefore there exists a need for a crib with a mattress that can be adjusted easily and quickly without causing any injuries to children and parents.